Definition
ChEBI: An optically active form of threonine having L-configuration.
Brand name
L -Threonine is JAN.
Biotechnological Production
L-Threonine can be produced using strains of E. coli or C. glutamicum. As threonine
is also an amino acid of the aspartate family, aspartate semialdehyde is a common
intermediate with the biosynthesis of L-lysine. In order to optimize a high-yielding
L-threonine–producing strain, the following strategy is applied: the pathway
towards L-lysine is minimized by reducing the activity of dihydrodipicolinate
synthase (dapA) and at the same time the pathway towards L-threonine is favored by
overexpression of the genes of the threonine operon, which consists of the genes for
homoserine dehydratase (thrA), homoserine kinase (thrB), and threonine synthase
(thrC). As L-threonine is also a precursor for L-isoleucine, further conversion of
L-threonine into L-isoleucine has to be minimized by deactivation of the threonine
dehydratase gene (ilvA). In the meantime, E. coli based strains have also been
developed by the application of systems biology, not only by deletion or
downregulation of the competing pathways such as L-lysine, L-methionine, and
L-isoleucine, but also by optimization of the supply of key precursors such as
oxaloacetate. The E. coli strain has been reported to produce 82 g/L L-threonine in
48 h with a carbon yield of 39 %. A more detailed description of the development
of a commercial L-threonine process has been given by Debabov.
Today L-threonine is manufactured on a commercial scale of several thousand
tonnes using the E. coli fermentation process.
General Description
This certified reference material (CRM) is produced and certified in accordance with ISO/IEC 17025 and ISO 17034. This CRM is traceable to primary material from an NMI, e.g. NIST or NMIJ.
Certified content by quantitative NMR incl. uncertainty and expiry date are given on the certificate.
Download your certificate at: http://www.sigma-aldrich.com.
Biochem/physiol Actions
L-Threonine is considered to be an essential amino acid. L-Threonine is involved in the synthesis of mucin, a protein supporting intestinal function and integrity. L-Threonine is required for the performance of the immune system. It is also essential for O-linked glycosylation, protein phosphorylation and glycine synthesis.
Purification Methods
Likely impurities are allo-threonine and glycine. Crystallise L-threonine from H2O by adding 4volumes of EtOH. Dry and store it in a desiccator. It also crystallises from 80% EtOH to give hexagonal plates m 262-263o(dec). It sublimes at 200-226o/0.3mm with 99.6% recovery and unracemised [Gross & Gradsky J Am Chem Soc 77 1678 1955]. [Elliot J Chem Soc 62 1950, Greenstein & Winitz The Chemistry of the Amino Acids J. Wiley, Vol 1 pp 176-183, Vol 3 pp 2238-2257 1961, Beilstein 4 IV 3171.]
